Among the more unique and impressive products are a set of route/path optimizers. They make constant speed, latency, congestion, and reliability measurements from thousands of points across the internet and use that data to send content through the most efficient paths possible.
Also, these services aren't just blanket across your domain or account - you can configure exactly what content gets what treatment based on literally hundreds of different variables. Furthermore, there are ways of having your origin servers send info to Akamai's edge caches that can then be used to make even smarter decisions, per-request.
I agree with other posters - it's expensive overkill for small sites or sites with modest needs, but for those who need maximum control, reliability and performance, I don't think there's any other company that provides it.